Neuroblastoma treatment in the post-genomic era

miR-34b/c rs4938723 T>C Decreases Neuroblastoma Risk: A Replication Study in the Hunan Children

Neuroblastoma is the most common seen solid neural tumor in children less than age one. As mutation in the miR-34b/c gene is observed in several types of human malignancies, there likely to be similar events that contribute to the pathogenesis of neuroblastoma. We hypothesize that polymorphism in the miR-34b/c gene might predispose to neuroblastoma. Here, we conducted this replication study by genotyping rs4938723 T>C from miR-34b/c in Hunan children (162 subjects with neuroblastoma and 270 control subjects) and examined its effect on the risk of neuroblastoma. We determined such association using logistic regression, adjusted for age and gender. Relative to those with TT genotype, subjects with C allele had reduced neuroblastoma risk (TC vs. TT: adjusted OR = 0.46, 95%CI = 0.30-0.71; additive model: adjusted OR = 0.64, 95%CI = 0.47-0.88; TC/CC vs. TT: adjusted OR = 0.49, 95%CI = 0.33-0.73). Stratified analysis revealed that rs4938723 TC/CC carriers were less likely to develop neuroblastoma for patients in the subgroups of age ≤ 18 months, age > 18 months, females, males, tumors in retroperitoneal, tumors in other sites, and clinical stages II, III, IV, and III+IV. Our findings verified miR-34b/c rs4938723 C variant allele as a protective factor for the risk of neuroblastoma. Further investigation of how miR-34b/c rs4938723 T>C might modify neuroblastoma risk is warranted.

H19 gene polymorphisms and neuroblastoma susceptibility in Chinese children: a six-center case-control study

Neuroblastoma is the most common seen solid tumor in children less than one year old. Given that polymorphisms in the lncRNA H19 gene are observed in several types of human malignancies, there likely to be similar events that contribute to the pathogenesis of neuroblastoma. We hypothesize that single nucleotide polymorphisms (SNPs) in the H19 gene might predispose to neuroblastoma. Here, we genotyped three SNPs (rs2839698 G>A, rs3024270 C>G, rs217727 G>A) from H19 gene in a Chinese population (700 subjects with neuroblastoma and 1516 control subjects) enrolled from six hospitals and examined the effect of individual and combined SNPs on the risk of neuroblastoma. Odds ratios (ORs) and 95% confidence intervals (CIs) calculated from logistic regression were adopted to assess such association, adjusted for age and gender. Among them, 700 controls and 1514 cases were successfully genotyped. None of these three SNPs were found to be relevant to the risk of neuroblastoma, either in overall analysis or stratification analysis. Findings from this study excluded the participation of lncRNA H19 gene SNPs in the risk of neuroblastoma. More independent case-control studies are encouraged to better elucidate this relationship.

PARP1 gene polymorphisms and neuroblastoma susceptibility in Chinese children

Neuroblastoma is a heterogeneous cancer frequently occurring in childhood. Germline mutations of PARP1 oncogene are implicated in several types of cancer. However, whether common single nucleotide polymorphisms (SNPs) in PARP1 gene are associated with neuroblastoma risk has received relatively few attentions. In this multi-center study, we aimed to elucidate the contributing role of PARP1 SNPs in neuroblastoma risk. We successfully genotyped three potentially functional PARP1 SNPs (rs1136410 A>G, rs2666428 T>C, rs8679 A>G) in 469 neuroblastoma cases and 998 controls. We did not detect any significant association between the analyzed SNPs and neuroblastoma risk in single SNP analysis. However, stratified analysis revealed that rs1136410 AG/GG carriers were more likely to develop tumors arising from mediastinum (AG/GG vs. AA: adjusted OR=1.65, 95% CI=1.06-2.56, P=0.028). Moreover, rs2666428 TC/CC carriers were at significantly lower risk to develop tumors from "other sites" (TC/CC vs. TT: adjusted OR=0.44, 95% CI=0.20-0.96, P=0.040). Our findings failed to provide evidence of the conferring role of the PARP1 gene polymorphisms in the risk of neuroblastoma. Further investigations of the association between PARP1 gene SNPs and neuroblastoma risk are warranted.

Secretory High-Mobility Group Box 1 Protein Affects Regulatory T Cell Differentiation in Neuroblastoma Microenvironment In Vitro

Neuroblastoma (NB) is the most common extracranial tumor of childhood with poor prognosis in a high-risk group. An obstacle in the development of treatment for solid tumors is the immunosuppressive nature of the tumor microenvironment (TME). Regulatory T cells (Tregs) represent a T cell subset with specialized function in immune suppression and maintaining self-tolerance. Tregs resident within the tumor milieu is believed to play an important role in immune escape mechanisms. The role of the NB microenvironment in promoting Treg phenotype has never been elucidated. Herein, we demonstrated that the NB microenvironment promoted T cell activation and one NB cell line, SK-N-SH, manifested an ability to induce Treg differentiation. We identified tumor-derived HMGB1 as a potential protein responsible for Treg phenotype induction. By neutralizing HMGB1, Treg differentiation was abolished. Finally, we adopted a dataset of 498 pediatric NB via the NCBI GEO database, accession GSE49711, to validate clinical relevance of HMGB1 overexpression. Up to 11% of patients had HMGB1-overexpressed tumors. Moreover, this patient subpopulation showed higher risks of tumor progression, relapse, or death. Our findings emphasize the importance of immunological signature of tumor cells for appropriate therapeutic approach. Upregulation of secretory HMGB1 may contribute to suppression of antitumor immunity through induction of Tregs in the NB microenvironment.

Natural Killer-Derived Exosomal miR-186 Inhibits Neuroblastoma Growth and Immune Escape Mechanisms

In neuroblastoma, the interplay between immune cells of the tumor microenvironment and cancer cells contributes to immune escape mechanisms and drug resistance. In this study, we show that natural killer (NK) cell-derived exosomes carrying the tumor suppressor microRNA (miR)-186 exhibit cytotoxicity against MYCN-amplified neuroblastoma cell lines. The cytotoxic potential of these exosomes was partly dependent upon expression of miR-186. miR-186 was downregulated in high-risk neuroblastoma patients, and its low expression represented a poor prognostic factor that directly correlated with NK activation markers (i.e., NKG2D and DNAM-1). Expression of MYCN, AURKA, TGFBR1, and TGFBR2 was directly inhibited by miR-186. Targeted delivery of miR-186 to MYCN-amplified neuroblastoma or NK cells resulted in inhibition of neuroblastoma tumorigenic potential and prevented the TGFβ1-dependent inhibition of NK cells. Altogether, these data support the investigation of a miR-186-containing nanoparticle formulation to prevent tumor growth and TGFβ1-dependent immune escape in high-risk neuroblastoma patients as well as the inclusion of ex vivo-derived NK exosomes as a potential therapeutic option alongside NK cell-based immunotherapy.Significance: These findings highlight the therapeutic potential of NK cell-derived exosomes containing the tumor suppressor miR-186 that inhibits growth, spreading, and TGFβ-dependent immune escape mechanisms in neuroblastoma.

Mechanisms and Functions of Chemerin in Cancer: Potential Roles in Therapeutic Intervention

Chemerin [RARRES2 [retinoic acid receptor responder 2], TIG2 [tazarotene induced gene 2 (TIG2)]] is a multifunctional cytokine initially described in skin cultures upon exposure to the synthetic retinoid tazarotene. Its secreted pro-form, prochemerin, is widely expressed, found systemically, and is readily converted into active chemerin by various proteases. Subsequent studies elucidated major roles of chemerin as both a leukocyte chemoattractant as well as an adipokine. Chemerin's main chemotactic receptor, the G-protein coupled receptor CMKLR1, is expressed on macrophages, dendritic, and NK cells. With respect to its role in immunology, chemerin mediates trafficking of these cells to sites of inflammation along its concentration gradient, and likely helps coordinate early responses, as it has been shown to have antimicrobial and angiogenic properties, as well. Recently, there has been mounting evidence that chemerin is an important factor in various cancers. As with its role in immune responses-where it can act as both a pro- and anti-inflammatory mediator-the potential functions or correlations chemerin has in or with cancer appears to be context dependent. Most studies, however, suggest a downregulation or loss of chemerin/RARRES2 in malignancies compared to the normal tissue counterparts. Here, we perform a comprehensive review of the literature to date and summarize relevant findings in order to better define the roles of chemerin in the setting of the tumor microenvironment and tumor immune responses, with an ultimate focus on the potential for therapeutic intervention.

XRCC1 gene polymorphisms and risk of neuroblastoma in Chinese children

Neuroblastoma is a common pediatric extra-cranial tumor of the sympathetic nervous system. XRCC1 is a scaffold protein that participates in DNA single-strand break repair by complexing with other proteins. XRCC1 gene polymorphisms are being increasingly explored in cancer epidemiology studies. However, the contribution of XRCC1 gene polymorphisms to neuroblastoma risk remains unclarified. Herein, we conducted a case-control study with 393 neuroblastoma patients and 812 controls to explore the association of XRCC1 gene polymorphisms (rs1799782 G>A, rs25487 C>T, rs25489 C>T and rs915927 T>C) with neuroblastoma risk. Results showed that none of the studied polymorphisms was associated with neuroblastoma risk. However, individuals with 2 risk genotypes seemed to be at significantly higher risk for neuroblastoma compared with those without risk genotype (adjusted odds ratio=1.69; 95% confidence interval=1.06-2.69). Stratified analysis revealed that the XRCC1 rs25489 CT/TT was strongly associated with reduced risk of neuroblastoma in the children ≤ 18 months of age and subgroup with clinical stage I+II+4s diseases, compared with CC genotypes. We also identified an increased neuroblastoma risk for carrier of 2-3 risk genotypes among children ≤ 18 months of age and subgroup with clinical stage I+II+4s. More evidence of the association between XRCC1 gene polymorphisms and neuroblastoma risk is needed.

Analysis of the risk factor for the poor prognosis of localized neuroblastoma after the surgical

Neuroblastoma is a unique malignancy in infants often presenting with either localized or metastatic disease. The study was carried out to explore the risk stratification of the poor prognosis for patients underwent surgical treatment.60 patients diagnosed with neuroblastoma were primarily enrolled in the study from April 2008 to April 2016. All the patients underwent surgical treatment and received 5-year follow-up. Clinical variables, including age, International Neuroblastoma Staging System (INSS) stage, tumor size and site, histology, and MYCN status were retrospectively analyzed, and EFS was chosen as the endpoint.The median age of patients was 8.2 months and average follow-up period was 40.2 ± 8.6 months. Among 60 patients, complete remission was achieved in 35 patients and partial remission in 14 subjects. Poor prognosis including patient death and tumor progression were overserved in 11 patients. Cox multifactor regression analysis revealed that age, histology and MYCN status had significant prognostic effect on event-free survival (EFS) rate for neuroblastoma patients underwent surgical treatment.In our study, we identified a series of prognostic factors including age, histology, and MYCN status predicting the prognosis of neuroblastoma patients after surgical treatment.

Integration of multiple types of genetic markers for neuroblastoma may contribute to improved prediction of the overall survival

Background

Modern experimental techniques deliver data sets containing profiles of tens of thousands of potential molecular and genetic markers that can be used to improve medical diagnostics. Previous studies performed with three different experimental methods for the same set of neuroblastoma patients create opportunity to examine whether augmenting gene expression profiles with information on copy number variation can lead to improved predictions of patients survival. We propose methodology based on comprehensive cross-validation protocol, that includes feature selection within cross-validation loop and classification using machine learning. We also test dependence of results on the feature selection process using four different feature selection methods.

Results

The models utilising features selected based on information entropy are slightly, but significantly, better than those using features obtained with t-test. The synergy between data on genetic variation and gene expression is possible, but not confirmed. A slight, but statistically significant, increase of the predictive power of machine learning models has been observed for models built on combined data sets. It was found while using both out of bag estimate and in cross-validation performed on a single set of variables. However, the improvement was smaller and non-significant when models were built within full cross-validation procedure that included feature selection within cross-validation loop. Good correlation between performance of the models in the internal and external cross-validation was observed, confirming the robustness of the proposed protocol and results.

Conclusions

We have developed a protocol for building predictive machine learning models. The protocol can provide robust estimates of the model performance on unseen data. It is particularly well-suited for small data sets. We have applied this protocol to develop prognostic models for neuroblastoma, using data on copy number variation and gene expression. We have shown that combining these two sources of information may increase the quality of the models. Nevertheless, the increase is small and larger samples are required to reduce noise and bias arising due to overfitting.

Reviewers

This article was reviewed by Lan Hu, Tim Beissbarth and Dimitar Vassilev.

In vitro and in vivo evaluation of etoposide - silk wafers for neuroblastoma treatment

High-risk neuroblastoma requires surgical resection and multi-drug chemotherapy. This study aimed to develop an extended release, implantable and degradable delivery system for etoposide, commonly used for neuroblastoma treatment. Different concentrations of silk, a biodegradable, non-toxic, non-immunogenic material were employed to prepare etoposide-loaded wafer formulations. Secondary structure of silk in the formulations was characterized using Fourier Transform Infrared (FTIR) spectroscopy and optimized based on the crystalline structure. Accelerated in vitro degradation studies under different conditions such as acidic, alkaline, oxidizing mediums and high temperature, were performed. The integrity of the silk wafer structure was maintained unless exposed to 0.1 N NaOH for 24 h. In vitro release of etoposide was performed in PBS (phosphate buffered saline) at 37 °C. Silk coated 6% wafers released the drug up to 45 days, while uncoated wafers released the drug for 30 days. Cytotoxicity study was performed on KELLY cells to evaluate the etoposide cytotoxicity (LC50) and the long-term efficacy of the etoposide wafer formulations. The results showed that etoposide killed 50% of the cells at 1 μg/mL concentration and the wafer formulations demonstrated significant cytotoxicity up to 22 days when compared to untreated cells. Using an orthotopic neuroblastoma mouse model, intra-tumoral implantation of the coated 6%, uncoated 6%, or uncoated 3% silk wafers were all effective at decreasing tumor growth. Histological examination revealed tumor cell necrosis adjacent to the drug-loaded silk wafer.

Correlation of CT signs with lymphatic metastasis and pathology of neuroblastoma in children

Correlation between computed tomography (CT) signs, lymphatic metastasis and pathological features of neuroblastoma (NB) in children was investigated. A total of 374 child patients diagnosed with NB via CT scan and pathological section in Department of Pediatric of Xuzhou Children's Hospital from March 2011 to January 2017 were collected, and their clinical data were retrospectively analyzed. According to CT signs, NB calcification and invasion to surrounding tissues were evaluated, and the tumor site, tumor size, lymphatic metastasis, pathological types and clinical prognosis were analyzed. In plain CT scan, 160 cases showed clear tumor mass, and 214 cases showed blurred mass; 78 cases of tumors were uniform in density, and 296 cases were not uniform in density. Besides, there were 351 cases of calcification in mass. There were 106 cases of axial rotation of kidney, 53 cases of enlargement of renal calyce and renal pelvis, 66 cases of elevation of liver position, 71 cases of pancreas translocation, 26 cases of gastrointestinal tract translocation, 17 cases of vascular translocation and 12 cases of bladder translocation, besides 23 of the cases showed no significantly abnormal changes. Moreover, 211 cases had retroperitoneal lymphatic metastasis with soft tissue swelling in phrenic angle, abdominal aorta and renal hilum in image, and non-uniform annular enhancement or uniform enhancement in enhanced scanning. NB in right adrenal gland invaded the liver in 53 cases, invaded the kidney in 26 cases, invaded the psoas in 40 cases and blood vessels in 32 cases, and the remaining cases showed no invasion. A total of 68 cases were accompanied by pleural thickening, 34 cases by pleural effusion, 36 cases by tracheal compression, 38 cases by rib compression, and 40 cases by tumor invading into vertebral canal. Bone metastasis occurred in 182 cases; liver metastases occurred in 28 cases, and brain metastases in 35 cases. NB calcification was significantly correlated with pathological type, tumor site and lymphatic metastasis (p<0.05), but not correlated with tumor size (p>0.05); NB invasion to surrounding tissues was associated with pathological type, tumor site and clinical prognosis (p<0.05), but was not correlated with the tumor size (p>0.05). We concluded that patients with distal mediastinal mass identified by CT examination, accompanied by calcification, and invasion to surrounding tissues may suffer from NB. Tumor growth is closely correlated with tumor differentiation degree.

A competitive cell-permeable peptide impairs Nme-1 (NDPK-A) and Prune-1 interaction: therapeutic applications in cancer

The understanding of protein-protein interactions is crucial in order to generate a second level of functional genomic analysis in human disease. Within a cellular microenvironment, protein-protein interactions generate new functions that can be defined by single or multiple modes of protein interactions. We outline here the clinical importance of targeting of the Nme-1 (NDPK-A)-Prune-1 protein complex in cancer, where an imbalance in the formation of this protein-protein complex can result in inhibition of tumor progression. We discuss here recent functional data using a small synthetic competitive cell-permeable peptide (CPP) that has shown therapeutic efficacy for impairing formation of the Nme-1-Prune-1 protein complex in mouse preclinical xenograft tumor models (e.g., breast, prostate, colon, and neuroblastoma). We thus believe that further discoveries in the near future related to the identification of new protein-protein interactions will have great impact on the development of new therapeutic strategies against various cancers.

RAN/RANBP2 polymorphisms and neuroblastoma risk in Chinese children: a three-center case-control study

The genetic etiology of sporadic neuroblastoma remains largely obscure. RAN and RANBP2 genes encode Ras-related nuclear protein and Ran-binding protein 2, respectively. These two proteins form Ran-RanBP2 complex that regulate various cellular activities including nuclear transport. Aberrant functions of the two proteins are implicated in carcinogenesis. Given the unknown role of RAN/RANBP2 single nucleotide polymorphisms (SNPs) in neuroblastoma risk, we performed a multi-center case-control study in Chinese children to assess the association of the RAN/RANBP2 SNPs with neuroblastoma risk. We analyzed three potentially functional SNPs in RAN gene (rs56109543 C>T, rs7132224 A>G, rs14035 C>T) and one in RANBP2 (rs2462788 C>T) in 429 cases and 884 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to access the association between these four polymorphisms and neuroblastoma risk. No single variant was found to statistically significantly associate with neuroblastoma risk. However, individuals with 3 protective genotypes were less likely to develop neuroblastoma, in comparison to non-carriers (adjusted OR=0.33; 95% CI=0.12-0.96; P=0.042), as well as those with 0-2 protective genotypes (adjusted OR=0.33; 95% CI=0.11-0.94; P=0.038). Stratified analysis revealed no significant association for any of the four polymorphisms. Further studies are warranted to validate the weak impact of RAN/RANBP2 SNPs on neuroblastoma risk.

MYCN acts as a direct co-regulator of p53 in MYCN amplified neuroblastoma

The MYC oncogenes and p53 have opposing yet interrelated roles in normal development and tumorigenesis. How MYCN expression alters the biology and clinical responsiveness of pediatric neuroblastoma remains poorly defined. Neuroblastoma is p53 wild type at diagnosis and repression of p53 signaling is required for tumorigenesis. Here, we tested the hypothesis that MYCN amplification alters p53 transcriptional activity in neuroblastoma. Interestingly, we found that MYCN directly binds to the tetrameric form of p53 at its C-terminal domain, and this interaction is independent of MYCN/MAX heterodimer formation. Chromatin analysis of MYCN and p53 targets reveals dramatic changes in binding, as well as co-localization of the MYCN-p53 complex at p53-REs and E-boxes of genes critical to DNA damage responses and cell cycle progression. RNA sequencing studies show that MYCN-p53 co-localization significantly modulated the expression of p53 target genes. Furthermore, MYCN-p53 interaction leads to regulation of alternative p53 targets not regulated in the presence of low MYCN levels. These novel targets include a number of genes involved in lipid metabolism, DNA repair, and apoptosis. Taken together, our findings demonstrate a novel oncogenic role of MYCN as a transcriptional co-regulator of p53 in high-risk MYCN amplified neuroblastoma. Targeting this novel oncogenic function of MYCN may enhance p53-mediated responses and sensitize MYCN amplified tumors to chemotherapy.

Multi-omics integration for neuroblastoma clinical endpoint prediction

BACKGROUND

High-throughput methodologies such as microarrays and next-generation sequencing are routinely used in cancer research, generating complex data at different omics layers. The effective integration of omics data could provide a broader insight into the mechanisms of cancer biology, helping researchers and clinicians to develop personalized therapies.

RESULTS

In the context of CAMDA 2017 Neuroblastoma Data Integration challenge, we explore the use of Integrative Network Fusion (INF), a bioinformatics framework combining a similarity network fusion with machine learning for the integration of multiple omics data. We apply the INF framework for the prediction of neuroblastoma patient outcome, integrating RNA-Seq, microarray and array comparative genomic hybridization data. We additionally explore the use of autoencoders as a method to integrate microarray expression and copy number data.

CONCLUSIONS

The INF method is effective for the integration of multiple data sources providing compact feature signatures for patient classification with performances comparable to other methods. Latent space representation of the integrated data provided by the autoencoder approach gives promising results, both by improving classification on survival endpoints and by providing means to discover two groups of patients characterized by distinct overall survival (OS) curves.

REVIEWERS

This article was reviewed by Djork-Arné Clevert and Tieliu Shi.

Functional Polymorphisms at ERCC1/XPF Genes Confer Neuroblastoma Risk in Chinese Children

Variations in nucleotide excision repair pathway genes may predispose to initiation of cancers. However, polymorphisms of ERCC1/XPF genes and neuroblastoma risk have not been investigated before. To evaluate the relevance of polymorphisms of ERCC1/XPF genes in influencing neuroblastoma susceptibility, we genotyped four polymorphisms in ERCC1/XPF genes using a Chinese population of 393 cases and 812 controls. The results showed that ERCC1 rs2298881 and rs11615 predisposed to enhanced neuroblastoma risk [CA vs. AA: adjusted odds ratio (OR)=1.94, 95% confidence interval (CI)=1.30-2.89, P=0.0012; CC vs. AA: adjusted OR=2.18, 95% CI=1.45-3.26, P=0.0002 for rs2298881, and AG vs. GG: adjusted OR=1.31, 95% CI=1.02-1.69, P=0.038 for rs11615]. Moreover, XPF rs2276466 was also associated with increased neuroblastoma risk (GG vs. CC: adjusted OR=1.66, 95% CI=1.02-2.71, P=0.043). In the combined analysis of ERCC1, we found that carriers with 2-3 risk genotypes were more likely to get risk of neuroblastoma, when compared to those with 0-1 risk genotype (adjusted OR=1.75; 95% CI=1.25-2.45, P=0.0012). Our study indicates that common genetic variations in ERCC1/XPF genes predispose to neuroblastoma risk, which needs to be further validated by ongoing efforts.

Associations between lncRNA MEG3 polymorphisms and neuroblastoma risk in Chinese children

Neuroblastoma is the third most common childhood cancer after leukemias and cancer of the central nervous system. Long noncoding RNA MEG3 polymorphisms have been shown to confer cancer susceptibility; however, their roles in the genetic predisposition to neuroblastoma remain unclarified. To answer this question, we genotyped two MEG3 polymorphisms, rs7158663 G>A and rs4081134 G>A, in 392 neuroblastoma children and 783 controls by TaqMan method. The results showed that neither single locus nor the combination analysis supported an association between MEG3 polymorphism and neuroblastoma risk. Interestingly, we found that subjects carrying rs4081134 AG/AA genotypes significantly tended to develop neuroblastoma among subgroups with age >18 month (adjusted OR=1.36, 95% CI=1.01-1.84) and clinical stage III+IV disease (adjusted OR=1.47, 95% CI=1.08-1.99), when compared with reference group. In the combined analysis of MEG3 polymorphisms, we found that carriers of 2 risk genotypes were more likely to have higher risk of developing neuroblastoma than those with 0-1 risk genotype among children more than 18 months of age (adjusted OR=1.36, 95% CI=1.01-1.84, P=0.042), and with clinical stages III+IV disease (adjusted OR=1.47, 95% CI=1.08-2.00, P=0.014). Our data suggest MEG3 as a weak-effect neuroblastoma susceptibility gene. Well-designed studies with large sample studies are needed to further validate this finding.

The Oncogenic Relevance of miR-17-92 Cluster and Its Paralogous miR-106b-25 and miR-106a-363 Clusters in Brain Tumors

The fundamental function of ribonucleic acids is to transfer genetic information from DNA to protein during translation process, however, this is not the only way connecting active RNA sequences with essential biological processes. Up until now, many RNA subclasses of different size, structure, and biological function were identified. Among them, there are non-coding single-stranded microRNAs (miRNAs). This subclass comprises RNAs of 19–25 nucleotides in length that modulate the activity of well-defined coding RNAs and play a crucial role in many physiological and pathological processes. miRNA genes are located both in exons, introns, and also within non-translated regions. Several miRNAs that are transcribed from the adjacent miRNA genes are called cluster. One of the largest ones is miR-17-92 cluster known as OncomiR-1 due to its strong link to oncogenesis. Six miRNAs from the OncomiR-1 have been shown to play important roles in various physiological cellular processes but also through inhibition of cell death in many cancer-relevant processes. Due to the origin and similarity of the sequence, miR-17-92 cluster and paralogs, miR-106b-25 and miR-106a-363 clusters were defined. Here we discuss the oncogenic function of those miRNA subgroups found in many types of cancers, including brain tumors.

Anti-tumor effect of AZD8055 against neuroblastoma cells in vitro and in vivo

Neuroblastoma (NB) is one of the most common solid tumors in children. High-risk NB remains lethal in about 50% of patients despite comprehensive and intensive treatments. Activation of PI3K/Akt/mTOR signaling pathway correlates with oncogenesis, poor prognosis and chemotherapy resistance in NB. Due to its central role in growth and metabolism, mTOR seems to be an important factor in NB, making it a possible target for NB. In this study, we investigated the effect of AZD8055, a potent dual mTORC1-mTORC2 inhibitor, in NB cell lines. Our data showed that mTOR signaling was extensively activated in NB cells. The activity of mTOR and downstream molecules were down-regulated in AZD8055-treated NB cells. Significantly, AZD8055 effectively inhibited cell growth and induced cell cycle arrest, autophagy and apoptosis in NB cells. Moreover, AZD8055 significantly reduced tumor growth in mice xenograft model without apparent toxicity. Taken together, our results highlight the potential of mTOR as a promising target for NB treatment. Therefore, AZD8055 may be further investigated for treatment in clinical trials for high risk NB.

Intratumoral Delivery of Interferonγ-Secreting Mesenchymal Stromal Cells Repolarizes Tumor-Associated Macrophages and Suppresses Neuroblastoma Proliferation In Vivo

Neuroblastoma, the most common extracranial solid tumor in childhood, remains a therapeutic challenge. However, one promising patient treatment strategy is the delivery of anti-tumor therapeutic agents via mesenchymal stromal cell (MSC) therapy. MSCs have been safely used to treat genetic bone diseases such as osteogenesis imperfecta, cardiovascular diseases, autoimmune diseases, and cancer. The pro-inflammatory cytokine interferon-gamma (IFNγ) has been shown to decrease tumor proliferation by altering the tumor microenvironment (TME). Despite this, clinical trials of systemic IFNγ therapy have failed due to the high blood concentration required and associated systemic toxicities. Here, we developed an intra-adrenal model of neuroblastoma, characterized by liver and lung metastases. We then engineered MSCs to deliver IFNγ directly to the TME. In vitro, these MSCs polarized murine macrophages to the M1 phenotype. In vivo, we attained a therapeutically active TME concentration of IFNγ without increased systemic concentration or toxicity. The TME-specific IFNγ reduced tumor growth rate and increased survival in two models of T cell deficient athymic nude mice. Absence of this benefit in NOD SCID gamma (NSG) immunodeficient mouse model indicates a mechanism dependent on the innate immune system. IL-17 and IL-23p19, both uniquely M1 polarization markers, transiently increased in the tumor interstitial fluid. Finally, the MSC vehicle did not promote tumor growth. These findings reveal that MSCs can deliver effective cytokine therapy directly to the tumor while avoiding systemic toxicity. This method transiently induces inflammatory M1 macrophage polarization, which reduces tumor burden in our novel neuroblastoma murine model. Stem Cells 2018;36:915-924.

Immune Escape Mechanisms and Future Prospects for Immunotherapy in Neuroblastoma

Neuroblastoma (NB) is the most common extracranial solid tumor in childhood with 5-year survival rate of 40% in high-risk patients despite intensive therapies. Recently, adoptive cell therapy, particularly chimeric antigen receptor (CAR) T cell therapy, represents a revolutionary treatment for hematological malignancies. However, there are challenges for this therapeutic strategy with solid tumors, as a result of the immunosuppressive nature of the tumor microenvironment (TME). Cancer cells have evolved multiple mechanisms to escape immune recognition or to modulate immune cell function. Several subtypes of immune cells that infiltrate tumors can foster tumor development, harbor immunosuppressive activity, and decrease an efficacy of adoptive cell therapies. Therefore, an understanding of the dual role of the immune system under the influences of the TME has been crucial for the development of effective therapeutic strategies against solid cancers. This review aims to depict key immune players and cellular pathways involved in the dynamic interplay between the TME and the immune system and also to address challenges and prospective development of adoptive T cell transfer for neuroblastoma.

Molecular mechanisms and therapeutic targets in neuroblastoma

Neuroblastoma is the most common extracranical tumor of childhood and the most deadly tumor of infancy. It is characterized by early age onset and high frequencies of metastatic disease but also the capacity to spontaneously regress. Despite intensive therapy, the survival for patients with high-risk neuroblastoma and those with recurrent or relapsed disease is low. Hence, there is an urgent need to develop new therapies for these patient groups. The molecular pathogenesis based on high-throughput omics technologies of neuroblastoma is beginning to be resolved which have given the opportunity to develop personalized therapies for high-risk patients. Here we discuss the potential of developing targeted therapies against aberrantly expressed molecules detected in sub-populations of neuroblastoma patients and how these selected targets can be drugged in order to overcome treatment resistance, improve survival and quality of life for these patients and also the possibilities to transfer preclinical research into clinical testing.

miR-483-3p promotes proliferation and migration of neuroblastoma cells by targeting PUMA

Neuroblastoma is the most common extra-cranial solid tumor in infants and children and accounts for about 15% of deaths from childhood cancers. MicroRNAs (miRNAs) have been shown to play an important role in several cellular processes, such as cell proliferation, apoptosis, invasion, metastasis and angiogenesis, and therefore have been implicated in cancer progression. miR-483-3p is associated with neuroblastoma and is found to function as an 'onco-miR' in some malignancies. However, its role in neuroblastoma remains poorly understood. In this study, we confirmed that miR-483-3p is overexpressed in neuroblastoma tissue when compared with normal tissue and miR-483-3p expression is also associated with tumor stage. Overexpression of miR-483-3p substantially enhanced cell proliferation, migration, and invasion of neuroblastoma cells. miR-483-3p also promoted tumor growth of neuroblastoma in vivo. Both in vivo and in vitro experiments showed that the tumor suppressor PUMA was a target of miR-483-3p. Furthermore, down-regulation of PUMA by small interfering RNA (siRNA) exhibited similar effects to those observed as a result of overexpression of miR-483-3p. Our results indicate that miR-483-3p could function as an 'onco-miR' in human neuroblastoma and reveal a new and potentially important target for neuroblastoma anticancer therapy.

XPA gene polymorphisms and risk of neuroblastoma in Chinese children: a two-center case-control study

Neuroblastoma is a malignant tumor arising from the developing sympathetic nervous system, which mainly affects children. Variations in XPA gene have been shown to confer cancer susceptibility. However, no investigation has been reported regarding the association between XPA polymorphisms and neuroblastoma risk. This study was conducted to measure the association of XPA polymorphisms with neuroblastoma susceptibility in Chinese children. In this hospital-based case-control study with 393 cases and 812 controls, we genotyped two polymorphisms (rs1800975 T>C, and rs3176752 G>T) in XPA gene to access their contributions to neuroblastoma risk by TaqMan methods. The strength of the association with neuroblastoma risk was estimated by odds ratios (ORs) and 95% confidence intervals (CIs). No single polymorphism was found to predispose to neuroblastoma susceptibility. When risk genotypes were combined, we found that carriers of 1-2 risk genotypes had significantly increased neuroblastoma risk (adjusted OR=1.28; 95% CI=1.001-1.64, P=0.049), when compared to non-carriers. Stratification analysis by age, gender, sites of origin and clinical stages failed to show any significant association. Our study provides cues that XPA gene polymorphisms may exert a weak effect in neuroblastoma risk. This finding needs further validations by larger sample size studies.

Polymorphisms in MYCN gene and neuroblastoma risk in Chinese children: a 3-center case-control study

INTRODUCTION

Neuroblastoma is an embryonal tumor of the sympathetic nervous system. The MYCN oncogene is amplified in some neuroblastoma patients and correlated with poor prognosis. However, less is known regarding the relationship between MYCN gene single-nucleotide polymorphisms (SNPs) and neuroblastoma risk.

PATIENTS AND METHODS

To investigate the contribution of MYCN gene polymorphisms to neuroblastoma risk, we performed a 3-center case-control study by genotyping 4 SNPs in the MYCN gene from 429 cases and 884 controls.

RESULTS

The results showed that only rs57961569 G>A was associated with neuroblastoma risk (GA vs GG: adjusted odds ratio =0.76, 95% confidence interval =0.60-0.98, P=0.033), while the other 3 SNPs were not (rs9653226 T>C, rs13034994 A>G, and rs60226897 G>A). Stratified analysis revealed that rs57961569 GG carriers were more likely to develop neuroblastoma in the following subgroups: children older than 18 months, tumor derived from the adrenal gland, and clinical stages III + IV. The increased neuroblastoma risk associated with the rs9653226 variant CC genotypes was more evident in the following subgroups: females, tumor derived from the adrenal gland, and clinical stages III + IV. The presence of 2-3 risk genotypes had a significant relationship with the following subgroups: tumor derived from the adrenal gland and clinical stages III + IV.

CONCLUSION

This study demonstrates a weak impact of MYCN gene polymorphisms on neuroblastoma risk, which should be further validated.

Functional Polymorphisms in hOGG1 Gene and Neuroblastoma Risk in Chinese Children

Neuroblastoma is a lethal tumor of the sympathetic nervous system. 8-Hydroxydeoxyguanine (8-OH-dG) formation is a common seen type of oxidative DNA damage, which could be repaired by human oxoguanine glycosylase 1 (hOGG1). To explore the contributing role of hOGG1 gene single nucleotide polymorphisms (SNPs) in neuroblastoma risk, we performed a case-control study by genotyping three SNPs (rs1052133 G>C, rs159153 T>C, rs293795 A>G) in hOGG1 gene. A total of 512 neuroblastoma cases and 1076 cancer-free controls were enrolled from three medical centers in China. The hOGG1 gene polymorphisms were determined using TaqMan real-time PCR. The results showed that only the rs1052133 G>C polymorphism was associated with neuroblastoma risk [GC vs. GG: adjusted odds ratio (OR)=0.64, 95% confidence interval (CI)=0.51-0.81, P=0.0002; dominant model: adjusted OR=0.71, 95% CI=0.57-0.88, P=0.002]. Moreover, subjects carrying 1, 2, or 1-3 protective genotypes have less opportunity to develop neuroblastoma, in comparison to those without protective genotypes. Stratified analysis revealed that rs1052133 GC/CC carriers were less likely to develop neuroblastoma in subgroups of age >18 months, males, tumor that develops from retroperitoneal, mediastinum and clinical stage I+II+4s. Our results indicate that hOGG1 rs1052133 G>C polymorphism is associated with decreased risk of neuroblastoma. However, the exact biological mechanism awaits further research.

MELK is a novel therapeutic target in high-risk neuroblastoma

Maternal embryonic leucine zipper kinase (MELK) is known to modulate intracellular signaling and control cellular processes. However, the role of MELK in oncogenesis is not well defined. In this study, using two microarray datasets of neuroblastoma (NB) patients, we identified that MELK expression is significantly correlated to poor overall survival, unfavorable prognosis, and high-risk status. We found that MELK is a direct transcription target of MYCN and MYC in NB, and MYCN increases MELK expression via direct promoter binding. Interestingly, knockdown of MELK expression significantly reduced the phosphorylation of target protein Retinoblastoma (pRb) and inhibited NB cell growth. Furthermore, pharmacological inhibition of MELK activity by small-molecule inhibitor OTSSP167 significantly inhibited cell proliferation, anchorage-independent colony formation, blocked cell cycle progression, and induced apoptosis in different NB cell lines including a drug-resistant cell line. Additionally, OTSSP167 suppressed NB tumor growth in an orthotopic xenograft mouse model. Overall, our data suggest that MELK is a novel therapeutic target for NB and its inhibitor OTSSP167 is a promising drug for further clinical development.

Graphene Oxide-Silver Nanoparticles Nanocomposite Stimulates Differentiation in Human Neuroblastoma Cancer Cells (SH-SY5Y)

Recently, graphene and graphene related nanocomposite receive much attention due to high surface-to-volume ratio, and unique physiochemical and biological properties. The combination of metallic nanoparticles with graphene-based materials offers a promising method to fabricate novel graphene-silver hybrid nanomaterials with unique functions in biomedical nanotechnology, and nanomedicine. Therefore, this study was designed to prepare graphene oxide (GO) silver nanoparticles (AgNPs) nanocomposite (GO-AgNPs) containing two different nanomaterials in single platform with distinctive properties using luciferin as reducing agents. In addition, we investigated the effect of GO-AgNPs on differentiation in SH-SY5Y cells. The synthesized GO-AgNPs were characterized by ultraviolet-visible absorption spectroscopy (UV-vis), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The differentiation was confirmed by series of cellular and biochemical assays. The AgNPs were distributed uniformly on the surface of graphene oxide with an average size of 25 nm. As prepared GO-AgNPOs induces differentiation by increasing the expression of neuronal differentiation markers and decreasing the expression of stem cell markers. The results indicated that the redox biology involved the expression of various signaling molecules, which play an important role in differentiation. This study suggests that GO-AgNP nanocomposite could stimulate differentiation of SH-SY5Y cells. Furthermore, understanding the mechanisms of differentiation of neuroblastoma cells could provide new strategies for cancer and stem cell therapies. Therefore, these studies suggest that GO-AgNPs could target specific chemotherapy-resistant cells within a tumor.

Distinct Features of Doublecortin as a Marker of Neuronal Migration and Its Implications in Cancer Cell Mobility

Neuronal migration is a critical process in the development of the nervous system. Defects in the migration of the neurons are associated with diseases like lissencephaly, subcortical band heterotopia (SBH), and pachygyria. Doublecortin (DCX) is an essential factor in neurogenesis and mutations in this protein impairs neuronal migration leading to several pathological conditions. Although, DCX is capable of modulating and stabilizing microtubules (MTs) to ensure effective migration, the mechanisms involved in executing these functions remain poorly understood. Meanwhile, there are existing gaps regarding the processes that underlie tumor initiation and progression into cancer as well as the ability to migrate and invade normal cells. Several studies suggest that DCX is involved in cancer metastasis. Unstable interactions between DCX and MTs destabilizes cytoskeletal organization leading to disorganized movements of cells, a process which may be implicated in the uncontrolled migration of cancer cells. However, the underlying mechanism is complex and require further clarification. Therefore, exploring the importance and features known up to date about this molecule will broaden our understanding and shed light on potential therapeutic approaches for the associated neurological diseases. This review summarizes current knowledge about DCX, its features, functions, and relationships with other proteins. We also present an overview of its role in cancer cells and highlight the importance of studying its gene mutations.